Light-scattering Properties Research Articles

Evaluation of Light Absorption and Scattering Properties of in vivo Rat Brain Using Single Refl ection Probe with Multiple Fibers

Evaluation of Light Absorption and Scattering Properties of in vivo Rat Brain Using Single Refl ection Probe with Multiple Fibers

基片与不同方位多形态缺陷粒子的复合光散射特性分析

基片与不同方位多形态缺陷粒子的复合光散射特性分析

纺织纤维光散射特性的模拟与实验

纺织纤维光散射特性的模拟与实验

Hexagonal TiO2 microplates with superior light scattering for dye-sensitized solar cells

Anatase TiO2 microplates with hexagonal shape were synthesized by a hydrothermal method in water–ethanol solvent. The single-crystalline TiO2 microplate film exhibited high reflectance in the visible region due to the unique planar morphology. When used as the scattering overlayer in dye-sensitized solar cells (DSCs), such microplates effectively enhanced light harvesting and led to the increase of the photocurrent of the DSCs. As a result, a 16.3% improvement in conversion efficiency was achieved after introducing the TiO2 microplate scattering layer (7.91%), which also surpassed the commercial scattering overlayer. The comparative experiments between the microplates and TiO2 microrods further confirmed that such a planar morphology is more beneficial to light scattering and photovoltaic performance. The excellent light-scattering properties of plate-like TiO2 make it a promising candidate as a scattering material for DSCs.

Surface Texturing of Ga-Doped ZnO Thin Films by Pulsed Direct-Current Magnetron Sputtering for Photovoltaic Applications

In this study, Ga-doped ZnO (GZO) transparent conducting thin films were prepared by pulsed direct-current magnetron sputtering, providing good transparency and relatively low resistivity. The films were further etched in different aqueous solutions, 0.5% HCl, 5% oxalic acid, and 33% KOH, to modify their light-scattering properties. The results showed that film textured by 0.5% HClaq. for 30 s had total optical transparency of T total = 77.4% and haze value of H T = 0.16, with electrical resistivity of ρ = 4.9 × 10−4 Ω-cm. For film textured in 5% oxalic acid solution for 75 s, the lowest electrical resistivity of 4.3 × 10−4 Ω-cm was achieved with relatively high total optical transparency of T total = 75.1%, as well as a more ideal haze value of H T = 0.3. Film textured in 33% KOH solution for 135 s (500 nm thickness) had optimal electrical conductivity of 5.1 × 10−4 Ω-cm with T total = 75.6%, and a relatively low haze value of H T = 0.12. GZO film textured with an agitated etch of 5% oxalic acid at 300 K would be the most suitable candidate for photovoltaic applications due to its high transparency and good electrical conducting properties.

Light Scattering Properties of Highly Textured Ag/Al:Si Bilayer Back Reflectors

Highly textured Ag, Al and Al:Si back reflectors for flexible n-i-p silicon thin-film solar cells were prepared on 100--thick stainless steel substrates by DC magnetron sputtering and the influence of their surface textures on the light-scattering properties were investigated. The surface texture of the metal back reflectors was influenced by the increased grain size and by the bimodal distribution that arose due to the abnormal grain growth at elevated deposition temperatures. This can be explained by the structure zone model (SZM). With an increase in the deposition temperatures from room temperature to , the surface roughness of the Al:Si films increased from 11 nm to 95 nm, whereas that of the pure Ag films increased from 6 nm to 47 nm at the same deposition temperature. Although Al:Si back reflectors with larger surface feature dimensions than pure Ag can be fabricated at lower deposition temperatures due to the lower melting point and the Si impurity drag effect, they show poor total and diffuse reflectance, resulting from the low reflectivity and reflection loss on the textured surface. For a further improvement of the light-trapping efficiency in solar cells, a new type of back reflector consisting of Ag/Al:Si bilayer is suggested. The surface morphology and reflectance of this reflector are closely dependent on the Al:Si bottom layer and the Ag top layer. The relationship between the surface topography and the light-scattering properties of the bilayer back reflectors is also reported in this paper.

Effect of Mesoporous TiO2 Bead Diameter in Working Electrodes on the Efficiency of Dye‐Sensitized Solar Cells

Mesoporous TiO₂ beads with diameters of 320±50, 550±50, and 830±40 nm, comprising interconnected and densely packed TiO₂ nanocrystals, were used as working electrodes for dye-sensitized solar cells (DSCs). These electrodes possess high surface areas and superior light-scattering properties, which are ideal for DSC applications. Although the electrode prepared by using 320±50 nm beads demonstrated the highest dye loading and the electrode prepared by using 550±50 nm beads showed the best light-scattering properties in the wavelength region λ=400-800 nm, DSC devices with working electrodes composed of 830±40 nm beads achieved the highest power conversion efficiencies of 9.0 % after treatment with TiCl₄. A higher electron diffusion rate (4.35×10⁻⁴ cm² s⁻¹) and an extended electron lifetime (58 ms) were observed in DSCs composed of the largest beads, 830±40 nm, attributable to a reduced amount of inter-bead barriers and a relatively small percentage of TiO₂ nanocrystals on the surface of the beads, compared to cells containing 550±50 and 320±50 nm beads.

Angle- and Spectral-Dependent Light Scattering from Plasmonic Nanocups

As optical frequency nanoantennas, reduced-symmetry plasmonic nanoparticles have light-scattering properties that depend strongly on geometry, orientation, and variations in dielectric environment. Here we investigate how these factors influence the spectral and angular dependence of light scattered by Au nanocups. A simple dielectric substrate causes the axial, electric dipole mode of the nanocup to deviate substantially from its characteristic cos(2) θ free space scattering profile, while the transverse, magnetic dipole mode remains remarkably insensitive to the presence of the substrate. Nanoscale irregularities of the nanocup rim and the local substrate permittivity have a surprisingly large effect on the spectral- and angle-dependent light-scattering properties of these structures.

Engineering Photonic–Plasmonic Coupling in Metal Nanoparticle Necklaces

In this paper, by combining three-dimensional finite-difference time-domain simulations, dark-field scattering analysis, and surface-enhanced Raman spectroscopy (SERS) we systematically investigate the light-scattering and field localization properties of circular loops of closely spaced gold nanoparticles, or "nanoplasmonic necklaces", fabricated by electron-beam lithography on quartz substrates. In particular, we show that nanoplasmonic necklaces support two hybridized dipolar scattering resonances with polarization-controlled subwavelength localized fields (i.e., electromagnetic hot-spots), whose intensities are optimized by varying the necklace particle diameter and the particle number. Moreover, we show that strong field intensity enhancement is obtained for the particular necklace diameters where loop-localized photonic resonances efficiently couple to the broadband plasmonic modes, enabling a simple design strategy for the optimization of electromagnetic near-fields. Following the proposed approach, we design nanoplasmonic necklaces supporting stronger field intensity enhancement than traditional nanoparticle monomer and dimer arrays. Finally, by performing SERS experiments on nanoplasmonic necklaces coated with a pMA molecular monolayer, we validate the optimization of their near-field properties and demonstrate their potential for plasmon-enhanced spectroscopy and sensing.

Ab initio modeling of fused silica, crystal quartz, and water Raman spectra

Fused silica light-scattering properties are important for many industrial and laboratory applications. In this work, ab initio molecular dynamics employing periodic boundary conditions are used to simulate its structure and Raman scattering. Fused silica geometry is modeled as a frozen liquid, and the spectra are compared to those of crystal quartz. The method is tested also on Raman spectra of liquid water. Structural similarities between water and fused silica are discussed. The modeling agrees with experiment and suggests that most fused silica spectral features can be explained within the harmonic approximation. The combination of Raman spectroscopy with theoretical computations thus appears useful for structural studies of amorphous materials.

Scattering matrix method for optical excitation of surface plasmons in metal films with periodic arrays of subwavelength holes

We present the formulation of a scattering matrix method for the study of light-scattering properties of metal films. The method is employed for the study of the optical excitation of surface plasmons in a gold film of 15-230 nm thickness, patterned periodically with subwavelength nanoholes. The gold film is placed on a thick SiO2 wafer, and the nanoholes as well as the top side of the gold film are filled with H2O. Light is incident on the gold film from either the SiO2 or the H2O side. The extinction and reflectance spectra of the system, as well as the electromagnetic field distributions at certain characteristic wavelengths, are calculated. The extinction spectra show, depending on system parameters, one or several peaks in the visible wavelength range. The extinction peaks are found to be caused by surface plasmons. A simple model based on the dispersion relation for surface plasmons in an unperforated gold film is shown to predict the peak positions of the extinction for thick perforated films very well. Even for thin films, this simple model, which includes coupling of surface plasmons on both surfaces of the film, predicts peak positions of the extinction well if the hole diameter is small enough. As the hole diameter increases, the extinction peaks of thin films show redshifts. Extinction peaks caused by surface plasmons at the SiO2/Au interface in thick films exhibit strong redshifts when the film thickness is decreased. However, the extinction peaks caused by surface plasmons at the H2O/Au interface in thick films show a completely different behavior. In this case, the extinction peaks do not move noticeably when the film thickness is decreased. Instead, they are weakened and finally disappear. It is also found that each extinction peak is accompanied by an extinction dip and that a reflectance dip is located in the wavelength between the extinction peak and the dip. This arrangement of an extinction peak, a reflectance dip, and an extinction dip is a general property of the surface-plasmon excitation. The calculated electromagnetic field distributions in both thick and thin films show clearly the signature of the excitation of surface plasmons at the extinction peaks, the extinction dips, and the reflectance dips. In thick films with small holes, the electric-field strength in the vicinity of the holes is weak at wavelengths for which surface plasmons are excited. In contrast to this, for thin films at the surface-plasmon excitations, a much stronger electric field is seen in the vicinity of the holes. (Less)

The interaction of phenolic compounds with bacteria. I. Hexylresorcinol and Escherichia coli.

Abstract Various quantitative aspects of the interaction of hexylresorcinol with E. coli suspensions are described. The amounts of hexylresorcinol bound by the bacteria from solutions of varying concentrations were determined and the speed of this reaction and the influence of temperature on the extent of binding examined. The release of cellular constituents from the bacteria and the changes in the light-scattering properties of E. coli suspensions on addition of hexylresorcinol were also investigated. These results are discussed in relation to the site of antibacterial action of hexylresorcinol.

Does ultrafiltration have a lasting effect on the physico-chemical properties of the casein micelles?

The objective of this work was to determine if concentration of milk using ultrafiltration (in the absence of diafiltration) affects the physico-chemical properties of the casein micelles. The milk, once concentrated, was brought back to its original concentration and the physico-chemical properties as well as its susceptibility to rennet induced gelation were assessed. Although much is understood on the renneting behavior of concentrated milk, no information is available on how (or if) ultrafiltration per se modifies the properties of the micelles. Two times (2×) or five times (5×) concentrated milk (based on volume reduction) was prepared by ultrafiltration. Casein micelles were redispersed in their corresponding permeates and dialyzed against untreated skim milk. The stability of the casein micelles, their scattering properties, and the renneting properties were observed under the same volume fraction and ionic conditions of the skim milk control. There was a higher susceptibility to aggregation and a lower gel stiffness for the reconstituted micelles from the 5× milk compared to the 2× milk. 5× Ultrafiltration induced losses of calcium from the micelle, while 2× milk showed similar value as the control. The results suggest that the process of ultrafiltration affected the internal structure of the casein micelles, and this caused changes in the light-scattering properties and renneting functionality.

Surface texturing of sputtered ZnO:Al/Ag back reflectors for flexible silicon thin-film solar cells

Al-doped zinc oxide/silver (ZnO:Al/Ag) back reflectors for silicon thin-film solar cells with an n–i–p configuration were prepared on flexible stainless steel substrates by dc magnetron sputtering. The surface morphologies of the back reflectors were modified by changing the deposition temperature of the Ag films to improve the light-scattering properties on the back reflectors, resulting in the enhancement of the light-trapping effect in the solar cells. By elevating the deposition temperature from room temperature to 500 °C, the surface roughness of the Ag films increased from 6.62 to 46.64 nm. The films at 500 °C had coarse surface features with irregular grain size distributions between 200 and 900 nm, whereas the films produced at low temperatures below 100 °C had smooth surfaces consisting of small grains between 100 and 200 nm. Even after the 100-nm thick ZnO:Al films were deposited on the modified Ag surfaces, the surface microstructure of the ZnO:Al/Ag bilayers was similar to that of the Ag films. The surface roughness of bilayers increased from 7.12 to 39.30 nm with coarsening the Ag surfaces. Haze factor (a ratio of diffuse reflectance to total reflectance) of Ag films was enhanced remarkably from 59% to 74% in a wide wavelength range from 350 to 1100 nm with increasing the surface roughness of the Ag films from 6.62 nm to 46.64 nm. Enhancement in the haze factor was due to the increase of diffuse reflectance on the Ag films, because the total reflectance did not change much with increasing surface roughness of the Ag films. This increasing roughness indicated that the light scattering from the rough surface of the back reflectors improved. The enhanced light scattering from the back reflectors influenced the performance of the solar cells mainly in terms of the short-circuit current density ( J sc). Compared to the back reflectors with smooth surface features, leading to a J sc value of 9.94 mA/cm 2, the back reflectors with large surface roughness improved the J sc value of the solar cells to 13.36 mA/cm 2 without detrimental changes in the fill factor (FF) and open circuit voltage ( V oc); they eventually increased the conversion efficiency of the solar cells from 5.59% to 7.60%.

Alteration of skin light-scattering and absorption properties by application of sunscreen nanoparticles: A Monte Carlo study

We report about the results of our investigations on the alteration of optical properties of the superficial layer of human skin at four UV range wavelengths, 310, 318, 360 and 400 nm, by application of 35–200 nm-sized particles of titanium dioxide (TiO 2), silicon (Si) and zinc oxide (ZnO). The theoretical study based on combination of the Mie theory and Monte Carlo simulations reveals the optimal sizes of the nanoparticles minimizing the light transmittance for the considered wavelengths.

分形凝聚粒子的光散射特性研究

分形凝聚粒子的光散射特性研究

分形凝聚粒子的光散射特性研究

分形凝聚粒子的光散射特性研究

分形凝聚粒子的光散射特性研究

分形凝聚粒子的光散射特性研究

复杂烟尘凝聚粒子的光散射特性研究

复杂烟尘凝聚粒子的光散射特性研究

Scattering of polarized light by randomly oriented coated spheroidal particle

A computer method is described to calculate the light-scattering properties of randomly oriented, axially symmetric coated particles, in the framework of the T-matrix theory. Both the core and the shell can be axially symmetric nonspheroidal particles. Based on the coated spheroidal particle model, light scattering characteristics of water aerosols with an absorptive core (black carbon) are calculated. The effects of cores with different sizes and shapes are analyzed on extinction efficiencies, scattering efficiencies, absorption efficiencies, single scattering albedos, asymmetric parameters.